Admin/Config. Tools/Storage Manager
This page has two separate section one details EPM Disk Storage presenting how much disk space is used by each EPM, (i.e. Bazaar plugins). The other section details Local Disk Storage, this typically falls into two categories of file: Documents (i.e. those uploaded as part of an eprint) and Object Revisions (i.e. those capturing XML revisions of an eprint's metadata over time). These categories of files can then be managed. However, for a default EPrints installation there not really anything you can actively manage. The Storage Manager is really only useful to see how much space each of the categories of files takes up on disk.